When marking text for interlinear glossing, most affixes are separated with a hyphen, but infixes are separated with ⟨angle brackets⟩.

English

English has almost no true infixes (as opposed to tmesis), and those it does have are marginal. A few are heard in colloquial speech, and a few more are found in technical terminology.

Chemistry

Chemical nomenclature includes the infixes ⟨pe⟩, signifying complete hydrogenation (from piperidine), and ⟨et⟩ (from ethyl), signifying the ethylradical C2H5. Thus from the existing word picoline is derived pipecoline, and from lutidine is derived lupetidine; from phenidine and xanthoxylin are derived phenetidine and xanthoxyletin.

Colloquialisms

The infix ⟨iz⟩ or ⟨izn⟩ is characteristic of hip-hop slang, for example hizouse for house and shiznit for shit. Infixes also occur in some language games.

The ⟨ma⟩ infix, whose location in the word is described in Yu (2004), gives a word an ironic pseudo-sophistication, as in sophistimacated, saxomaphone, and edumacation. This exists as a slang phenomenon.

The use of 'expletive infixes' such as fucking and bloody, which are words rather than affixes, is known as tmesis.

Sanskrit uses a nasal infix as a characteristic mark of verbs of the seventh class, or gaṇa. This infix takes the form of -na- in strong forms and -n- in weak forms (changing to retroflex ṇ after r and to m before labial sounds). For the root रुध् rudh, meaning "to block or hinder," one has रुणध्मि ruṇadhmi "I block" but रुन्ध्मः rundhmaḥ "We block" in the present tense.

Arabic

Arabic uses a common infix, ⟨t⟩ ت for Form VIII verbs, usually a reflexive of Form I. It is placed after the first consonant of the root; an epenthetici- prefix is also added since words cannot begin with a consonant cluster. An example is اجتهدijtahada "he worked hard", from جهدjahada "he strove". (The words "ijtihad" and "jihad" are nouns derived from these two verbs.)

Austronesian and Austroasiatic languages

Infixes are common in Austronesian and Austroasiatic languages. For example, in Tagalog, a grammatical form similar to the active voice is formed by adding the infix ⟨um⟩ near the beginning of a verb. Tagalog has borrowed the English word graduate as a verb; to say "I graduated" a speaker uses the derived form grumaduate.

Khmer, an Austroasiatic language, has seven different infixes. They include the nominalizing infix ⟨b⟩, which derives lbeun 'speed' from leun 'fast' and lbong ' trial' from long 'to test, to haunt'.

In Malay thus its direct descendant Indonesian, there are at least 5 kinds of infixes (sisipan). They are ⟨el⟩, ⟨em⟩, ⟨er⟩, ⟨ah⟩, and ⟨in⟩. Examples are:

The word 'dulu' means "first" or "advance" or "olden", while 'dahulu' means "formerly"'.

The word 'kerja' means "work", while 'kinerja' means "performance"'.

Seri

In Seri, some verbs form the plural stem with infixation of ⟨tóo⟩ after the first vowel of the root; compare the singular stem ic 'plant (verb)' with the plural stem itóoc. Examples: itíc 'did s/he plant it?' and ititóoc 'did they sow it?'.

Similar processes

Tmesis, the use of a lexical word rather than an affix, is sometimes considered a type of infixation. These are the so-called 'expletive infixes', as in fan-fucking-tastic and abso-bloody-lutely. Since these are not affixes, they are commonly disqualified from being considered infixes.

Sequences of adfixes (prefixes or suffixes) do not result in infixes: An infix must be internal to a word stem. Thus the word originally, formed by adding the suffix -ly to original, does not turn the suffix -al into an infix. There is simply a sequence of two suffixes, origin-al-ly. In order for -al- to be considered an infix, it would have to have been inserted in the non-existent word *originly. The "infixes" in the tradition of Bantu linguistics are often sequences of prefixes of this type, though there may be debate over specific cases.

The Semitic languages have a form of ablaut (changing the vowels within words, as in English sing, sang, sung, song) that is sometimes called infixation, as the vowels are placed between the consonants of the root. However, this interdigitation of a discontinuous root with a discontinuous affix is more often called transfixation.